The divisions between the pro- and anti-marijuana crowds at the state House Judiciary Committee meeting were already clear last week when the young man who described himself as a recovering heroin addict approached the microphone.

As the man spoke about marijuana use leading kids to harder drugs and fears that medical marijuana from dispensaries would make it into teenage hands, the lines became even clearer.

Law enforcement officers and treatment counselors in the audience looked on with interest, some nodding their heads. Several members of the marijuana community snickered or exchanged incredulous whispers during the testimony.

In the debate over Colorado’s medical-marijuana system, there is no issue that is as sharply divisive as the system’s impact on young people.

To many members of the law enforcement community, the growth of the state’s medical-marijuana industry is a plague that threatens to increase marijuana use of all kinds among teens and young adults — with disastrous results for the state.

“The revenue generated from the marijuana industry,” state Attorney General John Suthers wrote to lawmakers in a letter opposing a bill to regulate dispensaries, “will not cover the societal costs we will all incur.”

To many members of the marijuana community, statements like that amount to fearmongering. Dispensary owners say they resent the implication that they are indifferent to the well-being of young people. Marijuana-legalization activists say law enforcement officials are inflating the drug’s dangers.

“Let’s teach our kids to be realistic,” said Bob Melamede, a University of Colorado at Colorado Springs biology professor and marijuana activist. “Let’s teach our kids that marijuana has huge benefits.”

The division has grown wider as both sides produce studies appearing to back their positions.

Delbert Elliott, a University of Colorado at Boulder sociology professor, said the University of Michigan’s “Monitoring the Future” study has shown that teenage marijuana use increases when perceptions about the drug’s dangers decrease.

Elliott, along with several addiction counselors, say they fear Colorado’s medical-marijuana system will bring such a dynamic to the state.

“I think we are loosing an addictive drug into our society, and we are not exercising the controls that we know from bitter experience should be used,” said Thomas Crowley, a psychiatry professor at the University of Colorado Denver’s Anschutz Medical Campus.

Melamede counters that a study by the pro-legalization Marijuana Policy Project showed teen marijuana use declined in medical-marijuana states. He argues the more medical marijuana becomes legitimized, the less marijuana becomes an outlet for rebellion.

“Children are not turned on by the thought of acting like sick old people,” Melamede said.

Josh Stanley, the owner of the Peace in Medicine dispensary in Denver, says dispensaries with strict inventory controls will limit the amount of illegal marijuana available.

Crowley said there’s no way to control what happens to marijuana once it leaves the dispensary.

Since Colorado’s medical-marijuana boom is still so new, there is little data about its impact on young people.

People under 21 make up a small percentage of the state’s medical-marijuana registry — about 3 percent for applications received through the end of September, according to state health department statistics. People under 25 make up about 15 percent. (More recent figures are not available because the health department is backlogged in processing applications).

Officials for a number of public school districts and universities say they have seen few students with medical-marijuana cards.

But Matthew Tomatz, a substance-abuse counseling specialist at the University of Colorado at Boulder, said he has seen more patients with cards.

“For students who do have a medical card, I find that it legitimizes the marijuana use so that they are less able to explore its impact on their lives,” Tomatz said.

But — in a nod to the ambiguity of the issue — he added that he sees only students who are having problems.

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